To meet increasingly growing user demands, in 2004, the 3rd Generation Partnership Project (3GPP) standardization organization initiated the Long Term Evolution (LTE) project for a wireless network evolution plan and the System Architecture Evolution (SAE) project for a core network evolution plan. A wireless network in the LTE project is an evolved universal terrestrial radio access network (E-UTRAN), a core network in the SAE project is an evolved packet core (EPC) network, and an E-UTRAN and an EPC constitute an evolved packet system (EPS). Network elements of an EPS include a mobility management entity (MME), a serving gateway (S-GW), a packet data network gateway (P-GW), and the like, where the MME is responsible for control plane mobility management, the S-GW is a user plane anchor of an E-UTRAN, and the P-GW is a user plane anchor of an EPC network.
In a network architecture of the foregoing EPC network, data of a user equipment (UE) can reach a packet data network (PDN) only after passing through at least three hops, namely, a base station, an S-GW, and a P-GW. To reduce a quantity of forwarding hops and a forwarding delay, an S-GW and a P-GW are generally combined into one physical device, that is, an access gateway (AG).
Based on the foregoing improved network architecture, when a UE moves from one AG to another new AG, AG handover is caused. When a UE is handed over from an old AG to a new AG, in order to route downlink data of the UE to the new AG, a router in a PDN needs to update a routing information record of the UE in a routing table of the router, and this leads to fragmentation (originally, an IP address segment maintained by each AG is continuous) of routing information in the routing table, thereby increasing time for route search and affecting forwarding efficiency.